Agricultural irrigation and spraying systems, such as center pivot machines, are commonly used to distribute water and/or fertilizer and the like to crops in a field. A center pivot machine typically includes, among other things, a central pivot communicating with a source of ground water, chemical, or both, a series of mobile support towers connected to the central pivot and to one another by truss-type framework sections, a plurality of elevated conduits supported by the framework sections, and a number of sprinkler heads, spray guns, drop nozzles, or other fluid-emitting devices spaced along the length of the conduits. The mobile support towers are supported on wheels that are typically driven to move the system in a generally circular path about the central pivot to distribute the water, chemical, or both to crops in a field.
Conventionally, irrigation machines that are connected to a source of ground water can have certain approved chemical fertilizers, herbicides and insecticides injected into the main conduit of the machine downstream from a check valve that guards the ground water source from contamination by the chemicals. This process is sometimes referred to as “chemigation.” Other more potent chemicals may be approved by the Environmental Protection Agency (“EPA”) only for field application by sprayers that are separate and distinct pieces of equipment from the irrigation machines. Such arrangements provide satisfactory performance in some respects, although those of ordinary skill in the art will appreciate that it is expensive to provide and maintain separate conduit and emitter systems for each of the water and chemical distributions.